To apply operators to a dynamic variable or to a static variable, you must wrap the chosen function in the double curly brackets syntax: {{}} , as seen in the following example. This example demonstrates the use of the array[:] slice function with a step dynamic variable. It extracts elements from the step output starting from index 2 (inclusive), to index 4 (exclusive). So, it retrieves the elements at indices 2 and 3.

{{ steps.last.output[2:4]}}

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Supported literals

The following literals are supported:

1. strings - single and double quotes (e.g. "hello", 'hello')
2. numbers - e.g. 103, 2.5, .5
3. arrays - e.g. [1, 2, 3]
4. maps - e.g. {foo: "bar"}
5. booleans - true and false
6. nil - nil

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Digit separators

Integer literals may contain digit separators to allow digit grouping into more legible forms.

Example:

10_000_000_000

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Accessing public properties

Public properties on structs can be accessed by using the . syntax. If you pass an array into an expression, use the [] syntax to access array keys.

foo.Array[0].Value;

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Functions and methods

Functions may be called using () syntax. The . syntax can also be used to call methods on an struct.

price.String();

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Supported operators

Operators are symbols or keywords that perform actions on values, like adding, comparing, or combining them. Supported operators include:

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Arithmetic operators

• + (addition)
• - (subtraction)
• * (multiplication)
• / (division)
• % (modulus)
• ** (pow)

Example:

life + universe + everything;

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Comparison operators

• == (equal)
• != (not equal)
• < (less than)
• > (greater than)
• <= (less than or equal to)
• >= (greater than or equal to)

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Logical operators

• not or !
• and or &&
• or or ||

Example:

life < universe || life < everything

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String operators

• + (concatenation)
• matches (regex match)
• contains (string contains)
• startsWith (has prefix)
• endsWith (has suffix)

To test if a string does not match a regex, use the logical not operator in combination with the matches operator:

not ("foo" matches "^b.+")

You must use parenthesis because the unary operator not has precedence over the binary operator matches.

Example:

"Arthur" + " " + "Dent";

Result will be set to Arthur Dent.

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Membership operators

• in (contain)
• not in (does not contain)

Example:

user.Group in ["human_resources", "marketing"];

"foo" in { foo: 1, bar: 2 };

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Ternary operators

• foo ? 'yes' : 'no'

Example:

user.Age > 30 ? "mature" : "immature";

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Built-in functions

• len (length of array, map or string)
• all (will return true if all element satisfies the predicate)
• none (will return true if all element does NOT satisfies the predicate)
• any (will return true if any element satisfies the predicate)
• one (will return true if exactly ONE element satisfies the predicate)
• filter (filter array by the predicate)
• map (map all items with the closure)
• count (returns number of elements what satisfies the predicate)

Examples:

Ensure all tweets are less than 280 chars.

all(Tweets, {.Size < 280})

Ensure there is exactly one winner.

one(Participants, {.Winner})

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Closures

• {...} (closure)

Closures allowed only with builtin functions. To access current item use # symbol.

map(0..9, {# / 2})

If the item of array is struct, it’s possible to access fields of struct with omitted # symbol (#.Value becomes .Value).

filter(Tweets, {len(.Value) > 280})

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Slices

• array[:] (slice)

Slices can work with arrays or strings.

Example:

Variable array is [1,2,3,4,5].

array[1:5] == [2,3,4]
array[3:] == [4,5]
array[:4] == [1,2,3]
array[:] == array

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Examples:

{{ steps.last.status == 'OK' }}
{{ steps.S1.output + ' ' + steps.S2.output }}
{{ steps.last.output contains "test" }}
{{ len(steps.last.output) }}
{{ steps.last.output[10:14] }}